1. Field of the Invention
This invention relates to techniques relating to successful RFID deployment. In particular, it relates to an apparatus and its accompanying system for automatic placement of RFID antennas and a method for obtaining a readable region for passive RFID Tags.
2. Description of Related Art
Radio-Frequency Identification (“RFID”) is an automatic identification method that relies on small electronic devices to transmit and receive radio frequency signal for the purpose of identification.
RFID devices are mainly grouped into readers and tags. An RFID reader is a device equipped with antennas to read data from and write data to an RFID tag via  demodulation of radio waves. An RFID tag consists of a small chip and an antenna; the chip picks up radio frequency signals beamed at it from a reader device, and beams back signals modulated with data anywhere from a couple of inches to up to 20 or 30 feet away. The chip is also capable of carrying up to a few kilobytes of data. The tag with a unique identification number can be attached to or incorporated into a product, animal, or person and the stored information can be remotely retrieved through the modulated signals by the reader device for identification of the attached object.
The radio frequency (“RF”) signal returned from the RFID tag can be received by the reader, and the strength of the signal can be measured using Received Signal Strength Indication (“RSSI”). RSSI is a generic radio receiver technology metric. The RSSI value is usually transparent to the user of the receiver, but it can be used to indicate the readability of the RFID tag.
There are two types of RFID tags: active and passive. Active tags generate RF signals actively using the power from their own batteries. Passive tags can only emit RF signals based on those received from the readers in proximity. Hence, the effective range, or signal strength, of active tags is generally larger than that of the passive tags. However, passive tags are cheaper and smaller than their active counterparts.
RFID technology has been used by thousands of companies for a decade or more, and the benefits of the RFID applications had been claimed to improve productivity and reduce operation cost. Until recently, the technology is widely applied to four main areas:     1) Supply Chain Management,    2) Identification,    3) Transportation, and    4) Anti-counterfeiting.
The performance of RFID devices, however, can vary significantly across different brands and models (e.g., Alien ALN-9554, Alien ALN-9540, Impinj IPJ_N_M_EA and Omron V750-D22M01-IM). A successful RFID deployment depends not only on the product specification and standard, but also on other variables such as reader collision, tag collision, the natural environment factors. As such, it is a nontrivial task to locate precisely whether the causes of an unsatisfactory RFID deployment are due to the problems with tag reading distance, tag orientation, antenna geometry, read rate, detuned frequencies, multi-path effects, readers' emitting power, or other factors. One may explore these factors using a trial and error approach. However, the exploration process is overly tedious, and the result is likely random.
Therefore, there is a need for an invention comprising a novel measurement system, including software and hardware solutions, to locate precisely the causes of an unsatisfactory RFID deployment.